The present invention relates to a method for obtaining valuable products, in particular proteins, from a native mixture of materials.
In this case, using the present invention, a processing as extensive as possible of this mixture of materials is to proceed to obtain valuable products.
DE 195 29 795 C2 discloses a method which permits oils or fats to be obtained. In this method, an aqueous pulp is separated in a centrifuge into solid and liquid components. To the aqueous pulp is added a fraction of 5-75% by weight, based on the liquid fraction of the pulp, of an organic solvent. DE 195 29 795 C2 here addresses the problem of isolating a clear oil phase, a water phase, and a solids phase freed from oil from the aqueous pulp. This method has proved fundamentally successful for obtaining oils, waxes and fats.
Known methods for protein production are protein isolate production at an alkaline pH, or protein concentrate production at an acidic pH, which are preferably used in the case of hexane-extracted meal, but which, in combination with the method of DE 195 29 795 C2 are not applicable to a protein-lecithin mixture without a prior energy-intensive drying step.
In the literature, further publications for producing protein products from deoiled raw materials are cited, for instance Kroll et al., “Rapssamenproteine—Struktur, Eigenschaften, Gewinnung und Modifizierung” [Rapeseed proteins—Structure, properties production and modification], Deutsche Lebensmittel-Rundschau, number 3, 2007, p. 109.
These methods generally proceed from deoiled raw materials. Typical test oil contents are 1-4%. Should this not be the case, solvent extractions are performed, in order to reduce the oil value to an unavoidable minimum. These raw materials must therefore be deoiled because the oil interferes many times in the familiar methods. It always remains in the anhydrous phase, and is therefore part of the dry matter. Therefore, it remains in the protein cake or protein concentrate, that is to say as an impurity of the protein.
Some methods also use filter techniques. The filters can become blocked with the oil fraction which is present in emulsified form. Protein losses in the protein isolate are associated therewith.
This is the established approach to protein concentrate production: washing the meals (intensively deoiled), wherein the soluble extracted materials are depleted. The value of the deoiled intermediate products depends greatly on the concentration of accompanying materials, such as fibers, sugars and secondary plant materials (Menner, M. et al. “Fraktionierung pflanzlicher Rohstoffe zur simultanen Erzeugung von Lebensmitteln, technischen Rohstoffen und Energietragern” [Fractionation of plant raw materials for simultaneous generation of foods, industrial raw materials and energy carriers], Chemie Ingenieur Technik, volume 81, issue 11, pages 1743-1756, November 2009).
These accompanying materials also include polyphenols such as sinapine. In order to separate off these materials, high dilutions are selected, also proteins are denatured (temperature, alcohol), cellulose is enzymatically degraded to form short-chain carbohydrates; these methods are selected in order to be able to extract the materials better.
Protein concentrates remain behind, the protein fraction of which is increased if, in advance, hulling was performed which reduces the hull fraction and/or the cellulose fraction.
All of the methods have in common the fact that soluble proteins (albumins, some globulins) are co-extracted together with the polyphenols, carbohydrates and other dissolved materials.
Other approaches proceed from a very fine comminution, but then, also, the cellulosic hull fragments have to be separated off from the protein. The smaller they are, the more difficult the classification is and the separation of the material in general. The protein concentrate phase remains contaminated. Thus, a mechanical comminution of the meal/cake or an intense shearing of the meal or cake dispersion, optionally further associated with an enzymatic treatment, always leads to smaller cellulose units down to short-chain carbohydrates. In the attachment (FIGS. 4a, b), it may be seen, by way of example, that a broken cake has a maximum in the granulometric distribution at about 600 μm, and only a little-expressed relative maximum at 8-10 μm.
By shearing, the volume fraction of the global maximum at approximately 600 μm is disadvantageously reduced from approximately 5.5% to approximately 4.5%, and in consequence thereof, the relative maximum of the small particles at approximately 8 increases to above 1%. The protein phase is grayer as a result.
These small particles are difficult to separate from the protein. Extraction remains as a method, in high dilutions or multi-stage.
DE 10 2011 050 905 A1 additionally discloses a method for obtaining proteins from native mixtures of materials in which a native mixture of materials is first finely comminuted and optionally, by addition of a liquid, processed to form a free-flowing pulp. The method in addition has the following steps: adjusting the pH of the pulp to an alkaline range; addition of at least one water-soluble organic solvent subsequently to the adjustment of the pH of the pulp; and separating off a protein phase from the pulp subsequently to the addition of the water-soluble solvent. In addition, separating off a solids phase having a hull fraction from the pulp before this phase separation is disclosed. Maintaining the sequence of these steps is particularly advantageous. In this case, in contrast to that in DE 195 29 795 C2, before the addition of the water-soluble organic solvent, a pulp pH is adjusted to an alkaline range. As a result, the solubility of the proteins in the aqueous medium is increased, they are partially solubilized and, if they are not completely dissolved, at least present finely distributed and voluminous in the solution and not in compact form as are the remaining solids. A complete solubility of the proteins is interfered with by the presence of a protein-lecithin mixture. Subsequently to the adjustment of the pH, the organic water-soluble solvent is added, as a result of which, inter alia, oil, in particular the triglycerides and nonpolar materials, are displaced from the solubilized protein suspension.
The method of DE 10 2011 050 905 A1 thus permits proteins of high purity to be obtained, since, inter alia, owing to the increase in solubility of the proteins, bonds, for example to contaminants of cellulose and/or hulls, and the like are also apparently loosened.
Usually, the first step is a pressing operation for deoiling or partial deoiling. In this case the hulls form a framework in order to form a press cake. Even in the case of hulled seed, a necessary minimum of hulls remains for the pressing.
Owing to the pressing operation, adherence of the proteins to the hulls occurs. In this case, the higher the pressing pressure or the temperature are, the firmer the cotyledon adheres to the hulls and the more difficult it is to separate it off later from the hulls to obtain protein. Protein losses are caused thereby.
Against this background, nevertheless, the object of the invention remains, optimizing further the obtaining of valuable materials from the native mixture of materials.
Hereinafter, an advantageous method variant of the invention will be explained in more detail, wherein the drawings will also be utilized.